Description
Enzyme immunoassay for the quantitative determination of Insulin-like Growth Factor-binding Protein 7 (IGFBP-7) in human serum, plasma, and urine samples. Quality controls are included with the kit. Developed and manufactured in Europe by PromedeusLab.
Summary
Insulin-like Growth Factor-binding Protein 7 (IGFBP-7) is a member of the insulin superfamily of growth promoting peptides, and is one of the most abundant and common growth factor polypeptides. IGFBPs are a class of secreted proteins that is able to interact with many ligands other than IGFs (1)
Currently, IGFBP-7 has been used as an early diagnosis and prognostic marker for acute renal insufficiency (AKI). IGFBP-7 and TIMP-2 concentrations in the urine of children after receiving injections of contrast medium increased faster than
SCr. The combination of IGFBP-7 and TIMP-2 was better than either analyte alone (the specificity was 80.0%, and the sensitivity was 81.2%) (2). Based on the results of two studies, the combined measurement of urine TIMP-2 and IGFBP-7 became a US FDA-approved biomarker for risk assessment of AKI in ICU patients (1).
IGFBP-7 has also been proposed as a potential prognostic biomarker in heart failure (HF). It provided prognostic information incremental to clinical variables NT-proBNP, and hsTnT (3).
Other Names
IGFBP7, IBP-7, IGF-binding protein 7, IGFBP-rP1, MAC25 protein, PGI2-stimulating factor, Prostacyclin-stimulating factor (PSF), Tumor-derived adhesion factor (TAF), UniProtKB# Q16270.
Principle of Method
The microtiter plate is coated with the antibody specifically binding the IGFBP-7. The human serum, plasma, or urine sample is incubated in the plate with the capture antibody.
The specimen is washed out and the specifically bound protein is incubated with HRP-labelled detection antibody. Unbound reagent is then washed out. Horseradish peroxidase (HRP) bound in the complex reacts with the chromogenic substrate (TMB) creating the blue colour. The reaction is stopped by addition of STOP solution (H2SO4).
The absorbance values are measured at 450 nm (optionally 450/630 nm) and are proportional to the concentration of IGFBP-7 in the specimen. The concentration of IGFBP-7 in unknown samples is determined from the calibration curve which is created by plotting the absorbance values against the standard concentration values.
Sample Types
Serum, Plasma, Urine
Typical Standard Curve
Assay Range: 0.125 ng/mL - 4 ng/mL
Sensitivity
The limit of detection, defined as a concentration of human IGFBP-7 giving absorbance higher than absorbance of blank + 3 standard deviations, is better than 0.031 ng/mL of sample.
Precision
Intra-Assay
| Test sample | Mean (ng/mL) | SD | CV |
| 1 |
84.2 | 4.2 |
5% |
| 2 |
90.0 |
4.3 |
5% |
Inter-Assay (Run-to-Run)
| Test sample | Mean (ng/mL) | SD | CV |
| 1 |
77.6 |
3.7 |
5% |
| 2 |
80.4 |
8.3 |
10% |
Accuracy
Dilution Linearity:
| Test sample | Dilution |
Measured Concentration (ng/mL) |
Expected Concentration (ng/mL) |
Yield |
| 1 |
85.8 |
- | - | |
| 1 | 2x | 41.0 |
42.9 |
96% |
| 1 | 4x | 17.7 |
21.4 |
83% |
| 1 | 8x | 8.56 |
10.7 |
80% |
| 2 |
93.4 |
- |
- | |
| 2 | 2x | 43.5 |
46.7 |
93% |
| 2 | 4x | 20.0 |
23.3 |
86% |
| 2 | 8x | 9.4 |
11.7 |
80% |
Spiking Recovery:
| Test sample | Spike (ng/mL) |
Measured Concentration (ng/mL) |
Expected Concentration (ng/mL) |
Yield |
| 1 |
- | 68.8 |
- | - |
| 1 | 160 |
250.2 |
228.8 |
109% |
| 1 | 80 |
162.4 |
148.8 |
109% |
| 1 | 40 |
121.9 |
108.8 |
112% |
Storage
The kit must be stored at 2–8 °C. The opened components can be stored for one week at 2–8 °C.
Usage
This assay is for in vitro research use only and is not for use in diagnostic procedures.
Resources
Summary References
-
Wang S, Chi K, Wu D, Hong Q. Insulin-Like Growth Factor Binding Proteins in Kidney Disease. Front Pharmacol. 2021 Dec 22;12:807119. doi: 10.3389/fphar.2021.807119. PMID: 35002740; PMCID: PMC8728008.
-
Sun Q, Kang Z, Li Z, Xun M. Urinary NGAL, IGFBP-7, and TIMP-2: novel biomarkers to predict contrast medium-induced acute kidney injury in children. Ren Fail. 2022 Dec;44(1):1201-1206. doi: 10.1080/0886022X.2022.2075277. PMID: 36120960; PMCID: PMC9518296.
-
Adamson C, Welsh P, Docherty KF, de Boer RA, Diez M, Drożdż J, Dukát A, Inzucchi SE, Køber L, Kosiborod MN, Ljungman CEA, Martinez FA, Ponikowski P, Sabatine MS, Morrow DA, Lindholm D, Hammarstedt A, Boulton DW, Greasley PJ, Langkilde AM, Solomon SD, Sattar N, McMurray JJV, Jhund PS. IGFBP-7 and Outcomes in Heart Failure With Reduced Ejection Fraction: Findings From DAPA-HF. JACC Heart Fail. 2023 Mar;11(3):291-304. doi: 10.1016/j.jchf.2022.09.004. Epub 2022 Nov 9. PMID: 36592046.
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